Hi Gregory, An ingenious idea! I guess it would work but I'd be a little bit concerned about the alignment of the predicted surface. For now, I'll try Facu's method and see how that goes.
Best, Martin On 29 Jan 2010, at 08:11 , Greg Snow wrote: > Another approach that might be simpler (or it may oversimplify and not give > good results) is to compute the distances between your points as the fish > swim, then use multi dimensional scaling (cmdscale function or others) to get > a set of points that represent those distances and do the rest of your > analysis on the transformed points. > > > -- > Gregory (Greg) L. Snow Ph.D. > Statistical Data Center > Intermountain Healthcare > greg.s...@imail.org > 801.408.8111 > > >> -----Original Message----- >> From: r-sig-geo-boun...@stat.math.ethz.ch [mailto:r-sig-geo- >> boun...@stat.math.ethz.ch] On Behalf Of Martin Renner >> Sent: Wednesday, January 27, 2010 1:07 AM >> To: r-sig-geo@stat.math.ethz.ch >> Subject: [R-sig-Geo] kriging as fish swim, not as crows fly >> >> Hi All, >> >> I want to kirg fish and seabird densities within an estuary which has >> several arms. Since neither organisms cross land, the appropriate >> distances would not be euclidian but over-water (as fish swim). There >> are several papers, describing this problem and how to deal with it >> (see below), but I have not found an easily accessible implementation. >> Is anybody aware of a solution in R? >> >> Best, >> Martin >> >> >> >> @article{Rathbun:1998aa, >> Author = {Rathbun, Stephen L.}, >> Journal = {Environmetrics}, >> Number = {2}, >> Pages = {109--129}, >> Title = {Spatial modelling in irregularly shaped regions: kriging >> estuaries}, >> Volume = {9}, >> Year = {1998}} >> >> @article{Little:1997aa, >> Author = {Little, Laurie S. and Edwards, Don and Porter, Dwayne >> E.}, >> Journal = {Journal of Experimental Marine Biology and Ecology}, >> Number = {1}, >> Pages = {1--11}, >> Title = {Kriging in estuaries: as the crow flies, or as the fish >> swims?}, >> Volume = {213}, >> Year = {1997}} >> >> >> >> >> Martin Renner >> US Geological Survey >> Alaska Science Center >> >> _______________________________________________ >> R-sig-Geo mailing list >> R-sig-Geo@stat.math.ethz.ch >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
